Its historic but not in my top 5 best trilogies of all time. Its a better trilogy than Pac-Bradley for sure.
It never reached the heights of some of the best trilogies like Ali/Frazier, Gatti/Ward, Bowe/Holyfield, Morales/Barrera, Harding/Andries, or other fight series like Marquez/Pacquiao, Vasquez/Marquez. Every fight in the Gonzalez/Estrada trilogy was consistently good but lacked drama, knockdowns, both men hurting eachother, no real standout rounds in the trilogy. Overall i'd say mid tier good or possibily very good trilogy overall, but not quite up there with some of the legendary trilogies.
Have yet to see the third fight but the first fight was one of the best fights of the decade and the second one should have been the fight of the year. It doesnt have a single fight as great as some other trillogies have like Morales/Barrera,Gatti/Ward,Ali/Frazier or Bowe/Holyfield but for the skill level and sustained action i would have it highly on my list not as high as the ones i mentioned but right after them. Somewhere between 5 and 10.
Pac/Marquez and Iz/Rafa weren't trilogoies......... If that's the case then let's include SRR/Lamotta
Thats why i said other notable fight series instead of trilogy, but just judging them series on the first 3 fights they're still better IMO.